Lower liner with integrated flow equalizer and improved conductance

ABSTRACT

A plasma processing chamber has a lower liner with an integrated flow equalizer. In an etching process, the processing gases may be unevenly drawn from the processing chamber which may cause an uneven etching of the substrate. The integrated flow equalizer is configured to equalize the flow of the processing gases evacuated from the chamber via the lower liner.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of co-pending U.S. patentapplication Ser. No. 12/099,007 (attorney docket No. APPM/012985), filedon Apr. 7, 2008, which is herein incorporated by reference.

BACKGROUND

1. Field

Embodiments of the present invention generally relate to a plasmaprocessing chamber having a lower chamber liner.

2. Description of the Related Art

Modern integrated circuits are complex devices that may include millionsof components on a single chip; however, the demand for faster, smallerelectronic devices is ever increasing. This demand not only requiresfaster circuits, but it also requires greater circuit density on eachchip. In order to achieve greater circuit density, minimal dimensions,or critical dimensions, of features of integrated circuit componentsmust be reduced as well.

Reduction in the critical dimensions of integrated circuit componentfeatures requires strict process uniformity across a substrate in orderto maintain high yields. One problem associated with conventional plasmaetch processes used in manufacturing of integrated circuits isnon-uniformity of an etch rate across the substrate. Such non-uniformitymay be due, in part, to a vacuum pump drawing an etching gas toward anexhaust port provided in an etch chamber and away from the substrate.Since gases are more easily pumped away from areas of the chamber thatare closest to the exhaust port, the etching gas is pulled toward theexhaust port and away from the substrate. This creates a non-uniformetch on the substrate positioned therein, which may significantlydecrease the performance of the resulting integrated circuit andsignificantly increase the cost of fabrication.

Therefore, a need exists for an apparatus for uniformly etching materiallayers during the manufacture of integrated circuits.

SUMMARY

In one embodiment, an integrated flow equalizer is provided in a plasmaprocessing chamber. In one embodiment, the integrated flow equalizer isconfigured to protect lower chamber walls from exposure to plasma and toallow improved gas flow conductance. In one embodiment, a lower chamberliner is elevated from a chamber bottom wall to create a highconductance plenum between the lower chamber liner and the bottom wall.In one embodiment, the lower chamber liner has an aperture formedtherethrough configured to equalize the flow of processing gas drawn bya vacuum pump in fluid communication with the plenum resulting inuniform plasma flow and uniform etching across a substrate situated inthe plasma processing chamber.

In one embodiment of the present invention, an apparatus for plasmaprocessing comprises a chamber body, a first chamber liner disposedwithin the chamber body, and a second chamber liner disposed within thechamber body below the first chamber liner. The second chamber liner iselectrically coupled to the first chamber liner. The second chamberliner is in an elevated position with respect to a bottom surface of thechamber body such that an annular plenum is defined between the secondchamber liner and the bottom surface of the chamber body. The secondchamber liner has an aperture formed therethrough and configured toequalize the flow of processing gas drawn by a vacuum pump in fluidcommunication with the plenum.

In another embodiment of the present invention, an annular chamber linerfor a plasma chamber comprises a bottom wall, an inner wall extendingupwardly from the bottom wall, and an outer wall extending upwardly andoutwardly from the bottom wall. The annular chamber liner has aplurality of slots extending through the bottom and outer walls. In oneembodiment, the slots equalize the flow of processing gas. The pluralityof slots is arranged such that at least one slot is present within eachquadrant of the annular chamber liner.

In another embodiment of the present invention, an etching apparatuscomprises a chamber body, a substrate support pedestal disposed in thechamber body, a gas introduction showerhead disposed in the chamberopposite the substrate support, and an upper chamber liner disposed inthe chamber body. The upper chamber liner is disposed in the chamberbody such that the substrate support pedestal, the gas introductionshowerhead, and the first chamber liner at least partially enclose aprocessing area. An annular baffle is coupled to and surrounds thesubstrate support pedestal. A lower chamber liner, comprising a bottomwall, an inner wall, and an outer wall sloping upwardly and outwardlyfrom the bottom wall, is provided below the annular baffle and surroundsthe substrate support pedestal. The lower chamber liner is disposedwithin the chamber body such that an annular plenum is defined betweenthe bottom and outer walls of the lower chamber liner and a bottom andouter wall of the chamber body. The lower chamber liner has a slottherethrough to equalize the flow of processing as drawn by a vacuumpump in fluid communication with the plenum.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of theembodiments of the present invention can be understood in detail, a moreparticular description of the invention, briefly summarized above, maybe had by reference to embodiments, some of which are illustrated in theappended drawings. It is to be noted, however, that the appendeddrawings illustrate only typical embodiments of this invention and aretherefore not to be considered limiting of its scope, for the inventionmay admit to other equally effective embodiments.

FIG. 1 is a schematic cross-sectional view of an etching apparatusaccording to one embodiment of the invention.

FIG. 2A is a partial, schematic cross-sectional view of a lower chamberliner with an integrated flow equalizer according to one embodiment ofthe invention.

FIG. 2B is a schematic bottom view of the chamber liner in FIG. 2A.

FIG. 3 is a schematic bottom view of another embodiment of the lowerchamber liner of the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention generally comprise a plasmaprocessing chamber having a lower chamber liner with an integrated flowequalizer. Various embodiments of the present invention will bedescribed below in relation to an etching chamber. However, a variety ofplasma deposition and etching chambers may benefit from the teachingsdisclosed herein, and in particular, dielectric etching chambers such asthe ENABLER® etch chamber, which may be part of a semiconductor waferprocessing system such as the CENTURA® system, the PRODUCER® etchchamber, the eMax® etch chamber, among others, all of which areavailable from Applied Materials, Inc. of Santa Clara, Calif. It iscontemplated that other plasma reactors, including those from othermanufacturers, may be adapted to benefit from the invention.

FIG. 1 is a schematic cross-sectional view of an etching apparatus 100according to one embodiment of the present invention. The apparatus 100comprises a chamber body 102 in which a substrate 104 may be disposed ona pedestal 106 opposite a gas introduction showerhead 108. Processinggas may be supplied to the chamber 102 through the showerhead 108.Processing gas may be supplied to the chamber 102 through the showerhead108 from a gas source 110. In one embodiment, the pedestal 106 may bebiased with current from a power source 130. In another embodiment, theshowerhead 108 may be biased with a current from a power source 112.

During processing, the processing gas is supplied through the showerhead108 into the processing area 128 where the processing gas, in plasmaform, proceeds to etch material from the substrate 104. The plasma mayextend not only to the substrate 104, but it may extend to the chamberwalls as well. To protect the chamber walls from the plasma, an upperliner 126 may be present. The upper liner 126 may protect the chamberwalls from exposure to the plasma. Additionally, the upper liner 126 maybe removed during processing downtime to be cleaned or replaced.

An annular baffle 116 may surround the substrate 104 and the pedestal106. The annular baffle 116 may extend close to the upper liner 126 andhave a plurality of slots therethrough. The slots in the baffle 116permit processing gas to be drawn therethrough to be evacuated out ofthe processing chamber body 102. The slots may be sized to eliminate orreduce the amount of plasma that passes through the baffle 116.

Processing gas may also be drawn around the baffle 116 in the areabetween the baffle 116 and the upper liner 126. Generally, most of theplasma is confined to the processing area 128, but some plasma mayextend out beyond the outer diameter of the baffle 116 and be pulledbelow the baffle 116. A lower chamber liner 120 may be present toprotect the lower chamber walls from the plasma. The lower liner 120 maybe removed during processing downtime to be cleaned or replaced. Thelower liner 120 may be coupled to the bottom of the chamber body 102 bya fastening mechanism 124. In one embodiment, the fastening mechanism124 may comprise a screw. In one embodiment, the fastening mechanism 124may be countersunk into the lower liner 120.

A vacuum pump 114 may evacuate the processing chamber body 102 and thuspull processing gases through the baffle 116 and through the areabetween the baffle 116 and the upper liner 126. The lower chamber liner120 may be configured in an elevated position with respect to the bottomof the chamber body 102, such that a large plenum 122 may exist betweenthe bottom surface 121 of the lower chamber liner 120 and the bottomsurface 101 of the chamber body 102 around the entire periphery of thechamber body 102. Additionally, the lower chamber liner 120 may have anupwardly sloping outer wall 123, such that the plenum 122 extendsupwardly around the entire periphery of the lower chamber liner 120between the outer wall 123 of the lower chamber liner and the wall 103of the chamber body 102. The lower chamber liner 120 may contain aplurality of apertures (not shown in FIG. 1) to equalize the flow ofprocessing gas drawn therethrough. Example of suitable apertures can beseen in FIGS. 2B and 3. The large plenum 122 functions to broadlydistribute the vacuum draw. In one embodiment, the greatest draw throughthe lower chamber liner 120 may be achieved in the area closest to theexhaust port 113 in the chamber body 102, which may lead tonon-uniformity in the etch plasma across the substrate 104. In oneembodiment, to further promote, a uniform vacuum draw of process gasacross the annulus of the lower chamber liner 120, the size andpositioning of the apertures in the lower chamber liner 120 may bearranged as described below with respect to FIGS. 2B, and 3.

In addition, the lower chamber liner 120 is electrically coupled to theupper chamber liner 126, both of which are grounded. When an RF plasmais present, the RF current seeking a return path to ground may travelalong the upper liner 126 and/or the lower liner 120, whichever has thepath of least resistance. Electrically coupling the lower chamber liner120 to the upper chamber liner 126 provides substantial surface area forthe RF current seeking a path to ground. As a result, plasma may extendmore uniformly over the substrate 104 in the chamber 100, resulting inincreased etching uniformity.

FIG. 2A is a schematic, partial cross-sectional view of a lower chamberliner 200 according to one embodiment of the present invention. Thelower liner comprises an inner wall 202 that extends up from the bottomwall 204. The inner wall 202 protects the area under the pedestal fromplasma exposure. The outer wall 206 is upwardly sloping from the bottomwall 204 to the outer periphery of the lower chamber liner 200. Aplurality of gas passages 208 extend across and through the outer wall206 and the bottom wall 204 as depicted in FIGS. 2B and 3 and describedbelow.

FIG. 2B is a schematic bottom view of a lower chamber liner 200 of FIG.2A. As shown in FIG. 2B, the gas passages 208 in the bottom wall 204 andthe side wall 206 are broadly spaced apart in a first quadrant 210,which is to be positioned adjacent the exhaust port 113 in the chamberbody 102. The gas passages 208 may be more narrowly spaced in a secondquadrant 220 and a third quadrant 230 extending away from the firstquadrant 210 of the lower chamber liner 200. In one embodiment, thespacing of the gas passages 208 may decrease across the second quadrant220 and the third quadrant 230 extending away from the first quadrant210. In another embodiment, the gas passages may be equally spacedacross the second quadrant 220 and the third quadrant 230. The gaspassages 208 are most narrowly spaced across the fourth quadrant 240,which is to be positioned farthest from the exhaust port 113 of thechamber body 102.

FIG. 3 is a schematic bottom view of a lower chamber liner 300 accordingto another embodiment of the present invention. In this embodiment, thingas passages 307 are broadly spaced across the first quadrant 310 of thechamber liner 300, which is to be positioned adjacent the exhaust port113 in the chamber body 102. Mid-sized gas passages 308, which arelarger than the thin gas passages 307, are positioned more narrowlyacross the second quadrant 320 and the third quadrant 330 extending awayfrom the first quadrant 310. Large gas passages 309, which are largerthan the mid-sized gas passages 308, are positioned across the fourthquadrant 340 of the lower chamber liner 120, which is to be positionedfarthest from the exhaust port 113 of chamber body 102. The large gaspassages 309 are separated by thin, structural ribs. In one embodiment,a single gas passage 309 extends across the entire fourth quadrant 340.In another embodiment, the fourth quadrant 340 is divided into two gaspassages 309 having a single structural rib 341 therebetween.

By configuring the gas passages 208, 307-309 extending through the lowerchamber liner 120, 200, 300 such that the area farthest from the exhaustport 113 of the chamber 100 has the largest opening and the areaadjacent the exhaust port 113 has the smallest area, the uniformity ofvacuum draw from the processing area 128 may be increased.Correspondingly, by evening out the vacuum draw from the processing area128, the plasma distribution, and ultimately, etching uniformity may beincreased as well.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. An annular chamber liner for a plasma chamber, comprising: a bottomwall; an inner wall extending upwardly from the bottom wall; and anouter wall extending upwardly and outwardly from the bottom wall,wherein the annular chamber liner has a plurality of slots extendingthrough the bottom and outer walls, and wherein the plurality of slotsare arranged such that at least one slot is present within each quadrantof the annular chamber liner.
 2. The annular chamber liner of claim 1,wherein one quadrant of the annular chamber liner has fewer slots thanthe other three quadrants.
 3. The annular chamber liner of claim 1,wherein one quadrant of the annular chamber liner has a greater numberof slots than the other three quadrants.
 4. The annular chamber liner ofclaim 1, wherein one quadrant of the annular chamber liner has largerslots than the other three quadrants.
 5. The annular chamber liner ofclaim 1, wherein one quadrant of the annular chamber liner has smallerslots than the other three quadrants.
 6. An etching apparatus,comprising: a chamber body; a substrate support pedestal disposed in thechamber body; a gas introduction showerhead disposed in the chamberopposite the substrate support; an upper chamber liner disposed in thechamber body such that the substrate support pedestal, the gasintroduction showerhead, and the first chamber liner at least partiallyenclose a processing area; an annular baffle coupled to and surroundingthe substrate support pedestal; and a lower chamber liner, comprising: abottom wall; an inner wall configured below the annular baffle andsurrounding the substrate support pedestal; and an outer wall slopingupwardly and outwardly from the bottom wall, wherein the lower chamberliner has a slot formed therethrough and is disposed within the chamberbody such that an annular plenum is defined between the bottom and outerwalls of the lower chamber liner and a bottom and outer wall of thechamber body.
 7. The apparatus of claim 6, wherein the plenum is influid communication with an exhaust port.
 8. The apparatus of claim 6,wherein the lower chamber liner has a series of slots extendingtherethrough.
 9. The apparatus of claim 8, wherein one quadrant of thelower chamber liner has fewer slots than the opposing quadrant.
 10. Theapparatus of claim 8, wherein one quadrant of the lower chamber linerhas larger slots than the opposing quadrant.